The invention relates to improvements in methods of enhancing certain properties of parts which are made of a plastic material. The invention also relates to processed plastic parts which have undergone a treatment in accordance with the improved method. More particularly, the invention relates to improvements in parts of the type wherein a plastic carrier is coated, at least in part, with a film of aluminum or an aluminum alloy.
The German-language book entitled xe2x80x9cKunststoff-Me-tallisieurungxe2x80x9d (meaning xe2x80x9cMetallizing of Synthetic Plastic Materialsxe2x80x9d), published in 1991 by Eugen G. Leuze Verlag, Saulgau/Wdrttemberg, Federal Republic Germany, discloses (on page 75) a computer housing which is made of a plastic material and is provided with a layer of aluminum for the purpose of limiting the amount of electromagnetic radiation issuing from the computer. Page 83 of the same publication discloses the coating of polyester or polycarbonate foils with aluminum films. The purpose of such films is to render the foils impermeable to hydraulic fluids. The aforementioned publication fails to disclose or suggest the possibility of producing films or layers of aluminum or an aluminum alloy on shaped plastic articles for the purpose of imparting to such shaped articles a pronounced impermeability to fluids and/or other desirable properties in addition to or in lieu of impermeability to electromagnetic radiation.
An object of the present invention is to provide a novel and improved method of rendering shaped plastic products resistant to corrosion which is caused by climatic conditions and/or various chemicals with a pH in the range of between 5 and 8.
Another object of the instant invention is to provide a method which enables a shaped plastic article or product to constitute a highly satisfactory electric insulator.
A further object of the invention is to provide a method which enables a plastic product to resist penetration by a toxic substance.
An additional object of the invention is to provide a method which enables a shaped plastic product to with stand pronounced mechanical stresses, such as deforming stresses, as well as to withstand friction-induced wear.
Still another object of the invention is to provide a method which ensures that the shaped plastic article and its coating canot be readily separated from each other.
A further object of the invention is to provide a shaped plastic product wherein the feature that the article can exhibit the above-enumerated and/or other desirable characteristics contributes to the eye-pleasing appeal of the article.
Another object of the invention is to provide a simple but efficient and inexpensive method of enhancing one or more desirable characteristics of shaped plastic articles.
An additional object of the invention is to provide a clutch or another component part of a motor vehicle wherein one or more constituents are shaped plastic articles which have undergone a treatment in accordance with the present invention.
Still another object of the present invention is to provide a novel and improved actuating mechanism for utilization in or in conjunction with the clutch of a motor vehicle.
One feature of the present invention resides in the provision of an article of manufacture which is a shaped partly metallic and partly plastic member and comprises a plastic component having a surface, and an aluminum-containing oxidized metallic component which overlies and adheres to a portion or to the entire surface of the aforementioned plastic component. Adherence of the metallic component is the result of a chemical or an electrochemical treatment of the metallic component.
The metallic component can comprise or consist of aluminum oxide or of an oxide of an aluminum alloy.
The metallic component is or can constitute a layer or film having a thickness of between about 5 and 100 xcexcm.
Furthermore, the metallic component can comprise at least one coloring agent, and such metallic component can constitute a densified layer or film containing a material which is aluminum or an aluminum alloy.
The chemical or electrochemical treatment is or can be such that the metallic component is impermeable to fluids and/or that the metallic component exhibits a pronounced resistance to at least one of (a) penetration by fluids and (b) friction-induced wear.
The components (i.e., the partly metallic and partly plastic member) can form part of a clutch for motor vehicles. For example, the components can form part of a hydraulic cylinder which, in turn, can form part of an engaging-disengaging unit for clutches of motor vehicles.
Another feature of the present invention resides in the provision of a clutch for motor vehicles. The clutch comprises a cylinder member and a piston member which is reciprocable in the cylinder member. One of these members has a friction surface which is in sliding contact with a surface of the other member, and the one member includes a plastic component and a metallic component which is bonded to the plastic component and has a surface constituting at least a portion of the aforementioned friction surface. The metallic component consists of or contains oxidized aluminum and adheres to the plastic component as a result of a chemical treatment or an electrochemical treatment.
The thickness and/or the color of the plastic component can be selected as described hereinbefore. The same holds true for the permeability of the metallic component and/or for its resistance to wear.